I. Field of the Invention
The present invention relates generally to water heaters and, more particularly, to a microwave water heater.
II. Description of the Prior Art
Water heaters of the type commonly found in homes, apartment buildings, office buildings and other types of building constructions typically include a water tank having an outlet fluidly coupled to a fluid conduit system extending throughout the building construction. The tank also includes a fluid inlet coupled to a source of relatively cool water. In hot water heaters of the type used to provide running hot water in bathrooms, sinks and the like, the water pressure from the source is normally sufficient to establish fluid flow through the tank and into the fluid conduit system. Conversely, a pump is typically employed to establish fluid flow through the tank and fluid conduit system where the hot water system is closed, i.e., where the outlet from the fluid conduit system is coupled to the inlet of the tank. As is well known in the art, such closed hot water systems are used in hot water space heating systems. Previously, both natural gas and electrical resistance heating have been used as the heating means for heating the water in the water tank. Both of these heating means, however, are disadvantageous for a number of reasons.
First, both natural gas and electrical resistance heating are disadvantageous in that the heating of the water within the water tank is localized at either the flame or the electrical resistance coil, respectively. Such localized heating results in uneven temperature throughout the water in the water tank which is inefficient and results in energy losses. Although some of the disadvantages of these previously-known heaters have been overcome by microwave water heaters, these previously-known microwave heaters have also suffered several disadvantages. A chamber microwave heater such as that disclosed in U.S. Pat. No. 4,029,927 is disadvantageous in that the water is unevenly heated within the tank since the length of time in which the water is contained within the tank is not constant for all of the fluid entering the inlet.
Moreover, even in conventional water heaters wherein a tubing coil within the heating chamber prolongs the period in which the fluid is acted upon by the heating medium, such as disclosed in U.S. Pat. No. 3,778,578, a portion of the heat energy is not transferred to the fluid in the tubing but rather is wastefully imparted to the ambient air around the tubing and the tubing body itself. In addition, the heating medium must be constantly activated in order to transfer heat energy to the water. Thus, the heater is costly to operate.
A still further disadvantage of previously known natural gas and electrical water heaters is that the natural gas burner or the electrical resistance coil, respectively, is turned either completely on or completely off regardless of the amount of heating required by the water in the tank. This on-off operation of the previous-known water heaters also results in the inefficient use of energy.